1. Field of the Invention
The present invention relates to the field of liquid crystal device manufacturing techniques, especially relates to a manufacturing method for a switch and an array substrate.
2. Description of Related Art
Thin-film transistor (TFT) is one of the important elements of the array substrate and the thin film transistor technology is the core technology of the liquid crystal display, and it has a major impact on the quality of liquid crystal display.
In the manufacturing process of the thin film transistor, it generally goes through the cleaning, deposition, lithography, inspection and repair processes. The core process is photolithography mainly having photoresist coating, exposure, developing, etching, stripping, and other processes. When manufacturing metal traces of the thin film transistor on the base substrate, due to the resistivity of copper is smaller, it is more suitable for manufacturing the metal wire circuit for the large-size liquid crystal display device. Therefore, it generally uses copper for manufacturing the electrodes of the thin film transistor. However, copper is unfavorable for the photolithography process, and the adhesion force between the copper and the insulating layer containing silicon (Si) is relatively low. Therefore, in order to overcome the disadvantages of copper, before sputtering copper, it requires to add an adhesion layer containing molybdenum or titanium to increase the adhesion force between the copper layer and the insulating layer through molybdenum or titanium.
Specifically, as shown in FIG. 1, in step S1, firstly, after forming a gate electrode 11 of a thin film transistor on a glass base substrate 10, sequentially forming an insulating layer 12, a semiconductor layer 13, an ohmic contact layer 14, a molybdenum metal layer 15 above the gate electrode 11 and a copper metal layer 16 for forming a source electrode and a drain electrode of the thin film transistor, and then forming a photoresist layer 17 is on the copper metal layer 16. Then, it pattern the photoresist layer 17 to remove a portion of the photoresist layer 17 at a position 171 to expose a portion of the copper metal layer 16. In Step S2, etching the exposed copper metal layer 16 and the molybdenum metal layer 15 corresponding to and below the exposed copper metal layer 16 by utilizing an etching solution for copper. Thereby, it forms the source electrode and the drain electrode of the thin film transistor, and exposes a portion of the ohmic contact layer 14. In Step S3, it performs dry etching to the exposed ohmic contact layer 14 to realize the switching action of the thin film transistor. In Step S4, it uses the stripper to remove the photoresist layer 17.
In the above steps, on the one hand, due to the additional molybdenum metal layer 15, and on the other hand, it requires to etch the copper layer 16 and the molybdenum metal layer 15 using the etching solution for copper in the step S2. Therefore, when the etching selection ratio of copper to molybdenum is larger, it will cause that etching of the copper metal layer 16 has been finished to meet the requirements, but the etching of the molybdenum metal layer 15 is not completed. Therefore, it will result in the residue of the molybdenum metal. Although it can add the fluorine compound to the etching solution for effectively removing the molybdenum metal, the fluorine compound will also etch the glass base substrate 10, the insulating layer 12, the semiconductor layer 13 and the ohmic contact layer 14 such that the rework is impossible. Meanwhile, if the molybdenum metal cannot be removed, the residual molybdenum metal will impact the dry etching process of the ohmic contact layer 14 in step S3 such that the dry etching process cannot be performed smoothly, and the residual molybdenum metal will also lead to short circuit of the source electrode and the drain electrode, resulting in electrical abnormality of the thin film transistor.